1. Field of the Invention
The present invention relates to a clutch control apparatus of a vehicle for automatically controlling a frictional clutch for transmission of torque between a power source, such as an internal combustion engine, and a transmission, according to the state of operation of the vehicle. More particularly, the invention relates to a clutch control apparatus capable of absorbing characteristic errors in manufacture (variations among products) of a clutch disk and an actuator, which may be an electric motor.
2. Description of the Related Art
Conventionally, there has been known a clutch control apparatus for automatically engaging/disengaging a clutch through operation of an electrically controlled actuator, according to, for example, confirmation of a driver""s intention to change gears. Generally, in such a clutch control apparatus, a force generated by a diaphragm spring is transmitted to a clutch disk via a pressure plate to thereby engage the clutch disk with a flywheel under a predetermined press-contact load. In order to disengage the clutch disk from the flywheel, a force generated by the actuator is applied to the diaphragm spring so as to deform the same, to thereby reduce the press-contact load.
However, in the above-mentioned conventional clutch control apparatus, operating characteristics of a clutch in engagement/disengagement of the clutch (particularly, elapsed time in transfer of the clutch disk from the engaged state to the disengaged state or vice versa) vary among products, because of errors in manufacture and installation of the diaphragm spring or errors in manufacture of the actuator.
An object of the present invention is to provide a clutch control apparatus capable of compensating for the above-mentioned variation among products.
To achieve the above object, the present invention provides a clutch control apparatus for a vehicle, comprising: a clutch disk disposed opposite a flywheel, which rotates unitarily with an output shaft of a drive unit; a pressure plate for applying a press-contact load to said clutch disk so as to press said clutch disk toward said flywheel to thereby engage said clutch disk with said flywheel; a diaphragm spring for causing said pressure plate to generate the press-contact load; an actuator for generating and applying a force to a predetermined portion of said diaphragm spring by moving a member to deform said diaphragm spring for disengaging said clutch disk from said flywheel according to driving conditions of the vehicle; said clutch control apparatus further comprising: press-contact load adjustment means for modifying the press-contact load by modifying a posture of said diaphragm spring as observed when said clutch disk is engaged with said flywheel, according to an instruction; stroke estimation means for estimating a stroke of said member on the basis of an calculated ideal reaction force to be imposed on said member through said diaphragm spring and an estimated force generated by said actuator and; stroke detection means for detecting an actual stroke of said member; and adjustment instruction means for providing said press-contact load adjustment means with said instruction such that the detected stroke becomes equal to the estimated stroke to thereby make adjustment.
According to the present invention, stroke estimation means estimates a stroke of said member (e.g. a rod of the actuator) on the basis of an calculated ideal reaction force to be imposed on said member through said diaphragm spring and an estimated force generated by said actuator. That is, the stroke of the member is estimated on the assumption that a clutch operation system has designed characteristics (ideal characteristics). Simultaneously, stroke detection means detects an actual stroke of the member. The thus-detected stroke of the rod reflects all characteristic errors (for example, variations among products and installation errors) arising in manufacture of the clutch operation system. Accordingly, when press-contact load adjustment means modifies the press-contact load by modifying a posture of said diaphragm according to the instruction provided by the adjustment instruction means to make the detected stroke equal to the estimated stroke, characteristic errors which have arisen in the course of manufacture are compensated. Thus, substantially no variations are observed in clutching characteristics among products.
It is another object of the present invention to provide a clutch control apparatus which can compensate for the characteristic errors automatically without causing disadvantage to the normal driving of the vehicle by limiting the adjustment timing to a certain timing.
It is another object of the present invention to provide a clutch control apparatus that can compensate for the characteristic errors accurately by limiting the adjustment timing to a certain timing.
Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings.